The use of reaction mass actuators to absorb or suppress vibrations of structures has received considerable attention. In these systems, reaction mass actuators are typically actively controlled using inputs from accelerometers mounted to the device to determine the force required to be produced by the reaction mass actuator to cancel the structural vibrations. Conventionally, the reaction mass actuator control algorithms require high loop band widths which result in performance sensitivity to sensor noise and poor stability margins for broad-band or command-following control loops.
Vibrations are also recognized as a problem in rotating devices, for example in torpedo drive shafts. It has been recognized that the torpedo propeller causes axial vibrations of the rotating drive shaft that are transmitted to the torpedo body and radiate into the water as noise, allowing the torpedoes to be relatively easily detected. Accordingly, there is a great need to suppress axial vibrations of rotating structures, and vibrations caused by rotating structures.